The Rederivation, Cryopreservation, and Reconstitution groups within the Reproductive Sciences program at The Jackson Laboratory (TJL) serve Cancer Center members by ensuring that all strains imported to TJL are free of infectious and potential pathogens, and by providing access to Cryopreservation and assisted reproductive technologies that help investigators manage colonies more efficiently and guard against accidental loss, whether through breeding cessation or catastrophic loss. The Service further provides expertise and facilities for freezing embryos or gametes of strains; maintenance of frozen/stored material and associated information;recovery of strains from frozen material for research use;consultation and advice concerning freezing embryos or gametes;and teaching of Cryopreservation methods for others to use in their own laboratories where desired. These functions are absolutely essential to our operation as a research laboratory focused on mammalian genetics. The Reproductive Sciences program at TJL was created by combining the Rederivation, Cryopreservation, and Reconstitution program with Cell Biology and Microinjection. The Rederivation Program is being enhanced by the use of assisted reproductive technologies such as in vitro fertilization (IVF) and embryo transfer, both used routinely in the Cryopreservation program. Embryo transfer and IVF, not readily possible in TJL's older facilities, can now be carried out directly from imported mice in the Genetic Resources Building (GRB) facilities. This integration has facilitated the Cryopreservation of stocks upon their importation so that they ar.e backed up immediately. Working in tandem these programs located within the GRB have improved the efficiency with which strains from outside sources are rederived and cryopreserved, reducing the time to rederive strains by one half and reducing the time to rederive and cryopreserve strains from more than one year to a few months. Synergy of these programs with the Microinjection Service is also served by their new side-by-side location. Research Scientist Dr. Robert Taft was named Project Leader of Reproductive Sciences-Rederivation, Cryopreservation and Reconstitution in 2003. He oversees this fee-for-service operation, which occupies 12,232 ft2 of specialized laboratory, vivarium, procedure, and office space in the Genetics Resources Building. Dr. Taft communicates with the Cancer Center users, Service staff and Center Administration to ensure that research needs are met in the most efficient, cost-effective and technically current manner.